September weather forecast
Kalispell, MT

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A gorgeous sunset over the tranquil city of Kalispell, Montana
A gorgeous sunset over the tranquil city of Kalispell, Montana

Weather in September

Kalispell begins to transition into fall in September, creating an amalgamation of warm days and cooler nights. Despite the temperatures starting to drop, sunshine remains abundant, and the gradually decreasing daylight hours start to hint at the approaching winter. September distinguishes itself with only 0.04" (1mm) of snowfall - an annual low, 0.91" (23mm) of rainfall, and temperatures swirling from 39.9°F (4.4°C) to 65.7°F (18.7°C). This month thus stands out as the gateway between summer warmth and autumn chill.

Temperature

September in Kalispell brings a decrease in the average high-temperature, falling from August's moderately hot 77.4°F (25.2°C) to a comfortable 65.7°F (18.7°C). Despite considerable daily temperature swings, a steady low-temperature average of 39.9°F (4.4°C) is noted in Kalispell, Montana throughout September.

Humidity

The average relative humidity in September is 63%.

Rainfall

In Kalispell, in September, during 8.6 rainfall days, 0.91" (23mm) of precipitation is typically accumulated. Throughout the year, there are 142.8 rainfall days, and 17.36" (441mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall. September is the first month it typically snows in Kalispell. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, in Kalispell, there are 104.7 snowfall days, and 51.34" (1304mm) of snow is accumulated.

Daylight

In September, the average length of the day is 12h and 34min.
On the first day of September in Kalispell, sunrise is at 6:56 am and sunset at 8:17 pm. On the last day of the month, sunrise is at 7:36 am and sunset at 7:17 pm MDT.

Sunshine

In September, the average sunshine is 9.4h.

UV index

In September, the average daily maximum UV index in Kalispell is 3. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for the average person.
Note: The maximum daily UV index, 3 in September, converts into the following recommendations:
Exercise prevention - Warding off sunburn is urged. It's recommended to limit sun exposure when its radiation is at its peak during midday. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly. Forewarned is forearmed! The Sun's UV radiation can be almost doubled in intensity by snow reflection.
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Frequently asked questions

What is the average September temperature in Kalispell?

An average high-temperature, in September, in Kalispell, is 65.7°F (18.7°C) and the average low-temperature is 39.9°F (4.4°C).

What is the average humidity in September in Kalispell?

In September, the average relative humidity in Kalispell, Montana, is 63%.

How much does it rain in Kalispell in September?

In Kalispell, Montana, during September, the rain falls for 8.6 days and regularly aggregates up to 0.91" (23mm) of precipitation.

When does it start snowing in Kalispell?

September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow.

How many hours of daylight does Kalispell have in September?

In September, the average day length is 12h and 34min.

When are sunrise and sunset in September in Kalispell?

In September, on the first day of the month, sunrise is at 6:56 am and sunset at 8:17 pm. On the last day of the month, in Kalispell, sunrise is at 7:36 am and sunset at 7:17 pm MDT.

How long on average sun shines in September in Kalispell?

In September, the average sunshine duration in Kalispell is 9.4h.

What is the UV index intensity in September in Kalispell?

In Kalispell, Montana, the average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Kalispell, MT

Average temperature in September - Kalispell, MT
  • Average high temperature in September: 65.7°F

The warmest month (with the highest average high temperature) is July (77.5°F).
The month with the lowest average high temperature is December (25.9°F).

  • Average low temperature in September: 39.9°F

The month with the highest average low temperature is August (46.4°F).
The coldest month (with the lowest average low temperature) is February (14.4°F).

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Average pressure in September
Kalispell, MT

Average pressure in September - Kalispell, MT
  • Average pressure in September: 29.97"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in September
Kalispell, MT

Average wind speed in September - Kalispell, MT
  • Average wind speed in September: 3.8mph

The windiest month (with the highest average wind speed) is April (4.7mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).

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Average humidity in September
Kalispell, MT

Average humidity in September - Kalispell, MT
  • Average humidity in September: 63%

The month with the highest relative humidity is January (93%).
The month with the lowest relative humidity is August (55%).

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Average rainfall in September
Kalispell, MT

Average rainfall in September - Kalispell, MT
  • Average rainfall in September: 0.91"

The wettest month (with the highest rainfall) is June (2.05").
The driest month (with the least rainfall) is August (0.55").

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Average rainfall days in September
Kalispell, MT

Average rainfall days in September - Kalispell, MT
  • Average rainfall days in September: 8.6 days

The month with the highest number of rainy days is April (17.9 days).
The month with the least rainy days is August (6.6 days).

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Average snowfall in September
Kalispell, MT

Average snowfall in September - Kalispell, MT
  • Average snowfall in September: 0.04"

The month with the highest snowfall is January (11.3").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Kalispell, MT

Average snowfall days in September - Kalispell, MT
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is December (21.5 days).
The months with the least snowfall days are June, July and August (0 days).

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Average daylight in September /
Average sunshine in September
Kalispell, MT

Average daylight in September / Average sunshine in September - Kalispell, MT
  • Average daylight in September: 12h and 4min

The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).

  • Average sunshine in September: 9h and 2min

The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

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Average sunshine days in September
Kalispell, MT

Average sunshine days in September - Kalispell, MT
  • Average sunshine days in September: 19.6 days

The month with the most sunshine days is August (21.8 days).
The month with the least sunshine days is February (6.8 days).

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Average UV index in September
Kalispell, MT

Average UV index in September - Kalispell, MT
  • Average UV index in September: 3

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 1).

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Average cloud cover in September
Kalispell, MT

Average cloud cover in September - Kalispell, MT
  • Average cloud cover in September: 23

The month with the most cloud cover is January (Cloud cover 63).
The months with the least cloud cover are July and August (Cloud cover 15).

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Average visibility in September
Kalispell, MT

Average visibility in September - Kalispell, MT
  • Average visibility in September: 6mi

The months with the highest visibility are May, June, July, August, September and October (6mi).
The month with the lowest visibility is January (3mi).

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Kalispell, Montana, USA

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